1. Field of Invention
The present invention relates to an electrical connecting device, and more particularly to an extensible electrical connecting device which allows the extensible electric cord to have an adjustable length and at the same time to provide a power source to the work piece.
2. Description of Related Arts
Conventional extensible tubes used in a vacuum machine have many disadvantages. Their extensible mechanisms have complicated structures therefore the manufacturing cost is high and the installation and repair are difficult. It is also often found that their durability is low as that their performance drastically decreases after a period of use.